Rear projection device



INVENTOR.

S. V. COLLEY REAR PROJECTION DEVICE Filed Oct. 2, 1944 u l 20 ,o

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March l2., 1946.

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Patented Mar. 12, 1946 UNITED STATES PATENTA OFFICE (Granted under the act of March 3, 1883, as amended April 30, 1923; 370 0. G. 757) 1 Claim,

The invention described herein may be manufactured and used by or for the Government for governmental purposes, without the payment to me of any royalty thereon.

This invention relates to rear projection devices and more particularly to a projection device adapted to be used for purposes of classroom instruction. The principal object of my invention is to provide a rear projection device usable in conjunction with a conventional slide projection machine whereby a classroom instructor may stand substantially adjacent the screen for purposes of indicating portions of the image thereon during the course of a. lecture and have at the same time convenient access to the slide projection machine for changing slides. A further object of the invention is to provide a structure whereby models, such as airplane models and the like, may be interposed between a source of light and the rear of the screen for the purpose of producing a silhouette thereon to aid in aircraft identiilcation training. In accordance with the objects, I provide a projection device comprising a hood having an opening on one side through which rays from a projection machine may pass toward a reflecting surface at one end of the hood for reflection against a translucent screen at the other end thereof. The arrangement is such that the projection machine may be disposed adjacent the screen for the purposes `pointed out above. 'I'he 4other side of the hood is provided -with a door through which a model of an airplane or the like may be passed into the interior of the hood and held at the`rear of the screen by suspension from a rod held in the operator's hand. A, light beam from the projection machine, used in this case with no slide therein, is then reflected from the reflecting surface and casts a silhouetteof the model n the screen. A more detailed description of my invention now follows with reference to the appended drawing in which: l

1 is a sectional plan view through I-fI of 'd g. 2, an elevation looking toward the screen: n

Fig. 3 is a side view thereof.

With reference to the drawing, an elongated hood I is shown which may be of generally rectangular section supported by a truss frame indlcated by A, in any suitable manner. Disposed interlorly of the hood is a reflecting surface 3 such as s glass mirror 0r the like set at a suitable angle relative the longitudinal axis e( the hood so that light rays from a projection machine B disposed substantially exteriorly of the hood may be lreflected from the surface of mirror 3 to impinge upon a translucent screen 5. Projection machine B is removably supported on a shelf 7 which extends longitudinally of the side 8 of the hood. Shelf 'I forms the bottom wall of a tunnel-like structure comprised of a vertical wall lo and a top wall I I shielding from extraneous light a slot I3 in wall 8 through which the rays from projection machine B passes. A wall i8 opposite the wall 8 is provided with an opening I9 having a hinged door 20 through which a model of an airplane or the like may be held suspended for the purpose of casting a silhouette on screen 5. Ordinarily, when the device is used for silhouette recognition training, the projection Vmachine B is utilized without a slide for the purpose of obtaining a beam of light. However, it will be understood that slides showing backgrounds, e. g., cloud slides can be used in conjunction with airplane models, for the purpose of obtaining a realistic efl'ect, if so desired. When the device is used for purposes of slide projection, the door 20 is closed to prevent entry of. extraneous light into the hood.

It will be appreciated that in the structure' provided, an instructor may stand at the front of the device and have access to the projection machine for convenient operation of the slides, as well as being close enough to the screen to be able to point out pertinent portions of the projected image during the course of his lecture. Further, the device enables the instructor to substantially face the class during the course of his lecture in accordance with approved teaching methods.

Havingthus described my invention, I claim: In a projection device, a first hood comprising top, bottom and vertical walls, a translucent screen at one end 0L said hood and a reilecting surface at the opposite end thereof, an opening 'in a vertical wall of said hood, the planes of said opening, said reflecting surface and said screen having an angular relationship whereby light rays entering said hood through said opening are reflected fromsaid reflecting surface to said screen for the purpose of obtaining images on said screen f from a projection machine, said opening extending substantially the length of said hood whereby said projection machine may be disposed exteriorly of said hood and adjacent the screenA and a second hood shielding said opening exteriorly of said first hood and comprisinga shelf having a portion disposed to support said projection machine, said shelf being disposed intermediate the D andbottom walls of said first hood.

SHERRELLY.COLI.|EY. 

